The present invention relates to apparatus for manipulating a stream of sheets, especially a scalloped stream of partially overlapping paper sheets. More particularly, the invention relates to improvements in apparatus for separating discrete sections or shorter streams from a continuous stream of paper sheets or the like.
It is well known to subdivide the leader of a continuous scalloped stream of paper sheets into a succession of shorter streams or sections which are then subjected to further treatments, such as stacking into piles, gathering into signatures or the like. As a rule, the continuous stream is transported by a first conveyor which is driven at a given speed, and successive sections which are separated from its leader are transferred onto a second conveyor whose length at least matches that of a separated section. Each such section can be delivered into one of the magazines in a gathering machine or the like. As a rule, separation of discrete sections from the leader of the continuous stream is effected by resorting to an intercepting device which penetrates into the stream at certain intervals to temporarily prevent further forward movement of the sheets at its upstream side but to allow further forward movement of the sheets which constitute the thus separated section. This invariably entails the development of a pileup of a certain number of sheets immediately upstream of the intercepting device where the intercepted sheets accumulate into a stack which can present problems during further processing, i.e., subsequent to retraction of the intercepting device. A proposal to eliminate the development of stacks upstream of the intercepting device, whenever the latter is caused to penetrate into the stream, is disclosed in German Offenlegungsschrift No. 30 35 495. This publication proposes the formation of a small stack in response to alternate penetrations of the intercepting device into the continuous stream of partly overlapping sheets with attendant reduction of the frequency of problems which are likely to arise as a result of the accumulation of such stacks. This solution is evidently a stop-gap measure because it does not eliminate the aforediscussed problem but merely reduces the frequency of its development whereby the reduction of frequency is of little value when the stream is transported at an elevated speed so that the making of discrete sections must take place at rapidly recurring intervals.